Dinosaurs living together
Two Canadian scientists have new evidence about how such a startling variety of plant- eating species were able to survive in the same habitat.
Two Canadian scientists who examined the fossilized skulls of 82 individual dinosaurs from ancient Alberta have gathered powerful new evidence about how such a startling variety of enormous, plant- eating species were able to survive in the same habitat about 75 million years ago.
It turns out that evolution produced a respectful sharing of limited resources among the huge vegetarian beasts that lived together there during the Late Cretaceous era, a time when much of today’s Western Canada was part of a narrow, swampy island continent, Laramidia.
In a paper published Wednesday in the journal PLOS ONE, Canadian Museum of Nature and University of Calgary paleontologist Jordan Mallon and fellow U of C scientist Jason Anderson argue that subtle differences in the skulls of 16 species of big herbivorous dinosaurs show that they must have survived by “niche partitioning” — a delicate ecological balance in which each animal specialized in munching plants of certain types and heights to avoid competing directly with others for food.
Paleontologists, said Mallon, have been puzzling over the issue for a long time because there wouldn’t seem to have been enough plant resources to feed the large populations and multiple species of dinosaurs.
“It’s a mystery that keeps rearing its head in the last 10 or 20 years,” added Mallon. “How do you support that many species? There’s nowhere on Earth today where we can see that many large herbivores living at the same time, coexisting.”
There were several possibilities, he said, including a theory that vegetation growth was so phenomenal in the dinosaur age that food supplies were essentially “unlimited.”
But Mallon and Anderson reached a different conclusion based on skull differences.
“We found pretty good evidence for niche partitioning in these animals,” Mallon said.
He compared the phenomenon to how the wide- muzzled white rhinoceros and its narrowsnouted cousin, the black rhino, feed on different types of plants in the same African ranges, avoiding a dietary overlap that would otherwise have them competing for the same limited resources.